If you’re serious about finding a job in any professional career, you have to be on LinkedIn. Also, if you have a job but might be interested in a new job, the advice is the same.

Hopefully you’ve already heard this from others and you already have a profile. In that case do research on how to beef it up and get more prospective employers to find it.

If you haven’t heard this, or you’ve just been lazy about getting going, then get on there now and put up a profile!

Here’s some interesting information from a recent Fortune article on how LinkedIn will fire up your career.

If you need a job, or just want a better one, here’s a number that will give you hope: 50,000. That’s how many people the giant consulting firm Accenture plans to hire this year. Yes, actual jobs, with pay. It’s looking for telecom consultants, finance experts, software specialists, and many more. You could be one of them — but will Accenture find you?

To pick these hires the old-fashioned way, the firm would rely on headhunters, employee referrals, and job boards. But the game has changed. To get the attention of John Campagnino, Accenture’s head of global recruiting, you’d better be on the web.

To put a sharper point on it: If you don’t have a profile on LinkedIn, you’re nowhere. Partly motivated by the cheaper, faster recruiting he can do online, Campagnino plans to make as many as 40% of his hires in the next few years through social media. Says he: “This is the future of recruiting for our company.”

Facebook is for fun. Tweets have a short shelf life. If you’re serious about managing your career, the only social site that really matters is LinkedIn. In today’s job market an invitation to “join my professional network” has become more obligatory — and more useful — than swapping business cards and churning out résumés.

Companies explain that LinkedIn is more effective at finding qualified candidates, but it’s also more cost effective as well since employers don’t have to pay a recruiter.